Powers: Like all N'Garai demons, Kierrok is immune to the effects of aging and terrestrial disease. He is superhumanly strong (class 75?) and resistant to damage, with tough, leathery skin, razor-sharp claws and teeth which are coated with a deadly poison which can be fatal to regular humans. He also had wings, allowing him to fly. When injured, Kierrok showed the ability to regenerate by draining some life energy from his opponents, weakening them in the process. Kierrok is one of a very small number of N'Garai with advanced intelligence, and he led and directed the others, who were extremely savage and bloodthirsty.

Bio:After escaping the Demogorge by traveling to another dimension, the Elder God Chthon created the N'Garai and populated them in their own dimension, creating Kierrok to rule over them.

At some point millions of years ago, the N'Garai, possibly led by Kierrok, ruled the Earth. They were defeated and driven back to their dimension by some force approximately one million years ago.

Cyclops, in a fit of rage over a teammate's death, lashed out with his energy beams in the middle of a forest, unintentionally destroying the top of a cairn which acted as a portal to the N'Garai's dimension. This released Kierrok on Earth. Kierrok immediately attacked the X-Men, knocking aside Colossus, Nightcrawler, Storm, and Cyclops with little effort before being violently torn apart by Wolverine. However, Kierrok regenerated by drawing on the life forces of the X-Men around him, weakening his enemies and renewing his attack. Professor X scanned Kierrok's mind, but was overwhelmed by the evil. Eventually, Storm flew into the forest and sealed the cairn through which Kierrok had come. With that, Kierrok disappeared, back the the dimension of the N'Garai.

The Cairn near the X-Mansion rose again, releasing a N'Garai demon onto the X-Mansion grounds. It confronted Wolverine, who had began regression into a feral state. After slaying the demon, Wolverine followed another demon into the N'Garai's native dimension and began slaughtering of the N'Garai, with no intention of returning to earth until all the N'Garai were killed. Wolverine and Nightcrawler confronted Kierrok, who wounded and was in turn wounded by Wolverine. Realizing that Wolverine could possibly kill him, Kierrok banished Wolverine and Nightcrawler back to earth and closed the Cairn.

Inspired by Wolverine's performance against Kierrok, the Ru'Tai, a slave caste of N'Garai, rebelled and overthrew their oppressors. Kierrok was slain and his eye was kept as an amulet by Pilgrimm, a leader of the Ru'Tai.